1. Field of the Invention
The present invention relates to vehicle braking systems, and more particularly pertains to a new and improved valve assembly utilizable with hydrualic brakes which causes the brakes on a trailer to be applied prior to the application of the brakes on the pulling vehicle.
2. Description of the Prior Art
The jackknifing of tractor trailer trucks while braking is a well known and recognized problem, and various devices have been invented which are directed to overcoming this problem. Most prior art devices are constructed in the form of combined mechanical and hydraulic actuating systems which sense a jackknifing and which then operate to couteract the same through forces being applied by mechanical components that are hydraulically operated. These prior art device have met with limited success as evidenced by their lack of commercial availability, and typical examples of these prior devices are to be found in U.S. Pat. No. 4,455,035 which issued to Ivony et al on June 19, 1984; U.S. Pat. No. 4,556,231 which issued to R. Schultz on Dec. 3, 1985; and U.S. Pat. No. 4,585,248 which issued to Miller et al on Apr. 29, 1986.
As can be appreciated, tractor trailer rigs by law are required to have brakes on the trailers as well as on the tractors. It can be furtehr appreciated that a proper independent actuation of the various available braking systems on a tractor trailer rig could prevent jackknifing. For example, if a trailer could be stopped more quickly than a tractor, there would be less tendency for the heavy trailer to slide past the tractor during rapid braking. However, a system which allows braking forces to be applied to a trailer prior to a tractor does not appear to be commercially available and a need for such a system apparently exists. In this regard, the present invention substantially addresses this need.